Sinopec, China's largest oil refiner, on Monday announced the discovery of two major shale oilfields in the east of the country with combined proven reserves of 180 million tonnes.

The confirmation of the Xinxing and Qintong oilfields, which was approved by China's Ministry of Natural Resources, is a strategic move to exploit and identify shale oil reserves in the country's continental rift basins.

Shale oil mainly refers to liquid hydrocarbons trapped in formations of shale rock that can be extracted for refining. It is often found in organic-rich shale and thin interlayers of carbonate rock, sandstone and siltstone.

The assessment is the first time to use China's independently developed industry standards for the estimation of shale oil and continental shale oil system data, providing experience for the improvement of technical specifications and the reserve evaluation of shale oil in the future, said Li Jinggong, head of the ministry's oil reserves assessment team.

The two oilfields show promise for high initial yields due to favorable fracturability and formation pressure, with test results indicating the likelihood of stable outputs over extended periods.

Sinopec is aiming to see an annual shale oil output of 2 million tonnes by the end of the 15th Five-Year Plan period (2026-2030), with an annual increase in proven reserves exceeding 100 million tonnes during the period.

The recoverable shale oil reserves in China, one of the world's major crude oil consumers, ranks third globally. Data from China's National Energy Administration shows that the country's crude oil production was 213 million tonnes in 2024, while its shale oil output surged to 6 million tonnes, a year-on-year increase of over 30 percent.